The present invention relates generally to improvements in safety belt retractor devices and it relates more particularly to an improved acceleration responsive, automatic locking safety belt retractor reel.
A conventional seat safety belt retractor reel device which is commonly employed in automobiles includes a reel which is spring biased to rotate in a belt retraction direction and a mechanism for locking the reel against belt extraction rotation in response to a predetermined positive or negative acceleration, that is, an acceleration or deceleration which occurs consequent to a collision or other emergency conditions of the car.
In acceleration responsive automatic locking reels of the above type, however, the acceleration sensing mechanisms are very sensitive so that even under normally encountered driving conditions the frequency of operation is very high and repeated many times in a short interval. In a locking mechanism in which the extraction of the seat belt is locked by means of the engagement of a ratchet wheel by a pawl, the top of the pawl tooth is occasionally concurrently located at the same position as that of a tooth of the ratchet wheel. Since the speed of rotation of the ratchet wheel is enhanced by the withdrawal or extraction force of the seat safety belt, the tooth top of the ratchet wheel outwardly repels the tooth top of the pawl to thereby prevent the engagement between the pawl and ratchet wheel. Under such conditions, it requires a considerable period of time for the pawl to resume its normal position and thus again achieve engagement with the ratchet wheel. In the course of this period, a considerable length of the seat belt is extracted from the retractor, thereby preventing the proper and optimum operation of the seat belt system.
Moreover, in extreme cases, the tooth top of either the pawl or the ratchet wheel is damaged, and the subsequent engagement there between becomes imperfect.
The conventional automatic locking safety belt retractor accordingly possesses important drawbacks and disadvantages. It is frequently unreliable and subject to rapid wear and damage and otherwise leaves much to be desired.